It is well known that exercising devices generally serve two purposes, the strengthening and rehabilitation of muscles. The older exercising devices generally use a series of pulleys and ropes for lifting weights. However, a recent developement has been the use of a frame that supports a body, actuating means mounted with the frame for movement by a portion of the body, and a double acting hydraulic cylinder that resists movement of the actuating means and thereby strengthen or rehabilitate the muscles in the portion of the body moving the actuating means. Some examples of these exercising devices are: a "Neck Exerciser" disclosed in U.S. Pat. No. 4,066,259, issued on Jan. 3, 1978; a "Fluid Resistance Type Leg Exerciser" disclosed in U.S. Pat. No. 4,185,818, issued on Jan. 29, 1980; and a "Leg Curl Exercising Device" disclosed in U.S. Pat. No. 4,254,949, issued on Mar. 10, 1981. The information relating to the operation and use of these devices is to be incorporated herein by reference.
Although these exercising devices work exceedingly well with the conventional double acting hydraulic cylinders, they are not as effective as desirable because no specific double acting hydraulic cylinder has been developed for use in such devices or that permits control of the amount of force necessary to move the actuating portion of the exercising devices.
Accordingly, it is an object of the present invention to provide an exercising device and a double acting hydraulic cylinder which resists movement in either direction of a slideably mounted piston as a piston rod attached to the piston is moved into or out of the cylinder.
Further, it is an object of the present invention to provide an exercising device and a double acting hydraulic cylinder which controls the amount of opposing force in the cylinder which thereby regulates the necessary force applied through a piston rod attached to a piston to the cylinder to move the rod into or out of the cylinder.
In accordance with the invention, an exercising device comprises a frame for supporting a human body, actuating apparatus mounted with the frame for movement by the portion of the body, and a double acting hydraulic cylinder connected to the frame for resisting movement of the actuating apparatus. The cylinder includes a container with first and second chambers for supporting a fluid disposed therein and passageways for placing the chambers in fluid communication with one another. A piston is slideably mounted within the first chamber for acting on the fluid disposed therein and the piston has a passageway for placing a portion of the first chamber on one side of the piston in fluid communication with the portion of the first chamber on the other side. A piston rod extends from the piston out of the container for moving the piston in response to movement of the actuating means and valve means are used for limiting fluid flow through a selected passageway from the first chamber to the second chamber. A control means is connected to the cylinder for governing the fluid flow through the selected passageway to regulate the amount of force necessary to move the actuating means.
Also in accordance with the invention, a double acting hydraulic cylinder comprises an inner tube disposed within an outer tube. Head and base members are used to close the ends of the tubes with each head and base member having a passageway for placing fluid disposed within the inner and outer tubes in communication. A piston is slideably mounted within the inner tube for acting on the fluid disposed therein and has a passageway extending therethrough for placing the fluid on one side of the piston in fluid communication with the fluid on the other side. A piston rod for moving the piston is mounted with the piston and extends through the head member to displace fluid in the inner tube. A first valve is mounted in the base member passageway to prevent fluid communication therethrough when the piston is moved toward the base member and a second valve is mounted in the piston passageway for preventing fluid communication therethrough when the piston is moved toward the head member. The valves and piston rod, thus, coact so that fluid in the inner tube will always flow through the head member passageway to the outer tube when the piston is moved.